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. 2020 Feb 21;64(3):e01772-19. doi: 10.1128/AAC.01772-19

TABLE 2.

In vitro activities of chitosan and its derivatives against amastigotes infecting PEMs, as well as cytotoxicities toward KB cells

Compound Mean value ± SD (μg/ml)a
Activity against amastigotes atb:
 Cytotoxicity toward KB cells at pH 6.5c
pH 7.5
 pH 6.5
L. major
 L. mexicana
 L. major
 L. mexicana
EC50 EC90 EC50 EC90 EC50 EC90 EC50 EC90 LD50 LD90
Amphotericin B 0.07 ± 0.01 0.13 ± 0.05 0.19 ± 0.05 1.5 ± 0.2 0.06 ± 0.01 0.11 ± 0.06 0.18 ± 0.06 1.7 ± 0.3 58 ± 8 190 ± 9
HMW chitosan 98 ± 6 1,635 ± 245 119 ± 9 1,804 ± 304 11.4 ± 1 69 ± 18 15.4 ± 2 103 ± 28 752 ± 90 3,022 ± 366
MMW chitosan 103 ± 8 1,652 ± 287 125 ± 10 1,793 ± 323 12.9 ± 1 81 ± 18 16.3 ± 2 122 ± 34 758 ± 89 3,019 ± 400
LMW chitosan 102 ± 7 1,651 ± 282 125 ± 10 1,795 ± 320 12.1 ± 1 74 ± 14 16.1 ± 2 116.6 ± 33 803 ± 90 3,088 ± 420
Fungal chitosan 102 ± 7 1,650 ± 276 124 ± 9 1,796 ± 316 12.6 ± 3 92 ± 27 16.9 ± 2 144 ± 44 759 ± 91 3,134 ± 380
Chitosan oligosaccharide 145 ± 12 2,473 ± 500 175 ± 14 2,543 ± 505 73 ± 4 260 ± 32 86.2 ± 6 288 ± 39 765 ± 93 3,232 ± 400
Chitosan oligosaccharide-lactate 93 ± 7 1,957 ± 174 120 ± 9 2,365 ± 239 39 ± 1 201 ± 16 47 ± 2 245 ± 23 754 ± 92 3,058 ± 390
Chitosan HCl 97 ± 11 2,080 ± 516 121 ± 15 2,402 ± 667 40 ± 2 210 ± 23 47.9 ± 3 243 ± 33 781 ± 92 3,589 ± 405
PC1-chitosand 144 ± 10 1,292 ± 217 169 ± 12 1,365 ± 212 68 ± 3 246 ± 26 81.7 ± 6 274 ± 38 756 ± 93 3,364 ± 398
PC2-chitosand 133 ± 6 1,005 ± 194 159 ± 6 1,705 ± 170 60 ± 3 202 ± 22 71.9 ± 5 237 ± 36 800 ± 92 3,709 ± 410
PC3-chitosand 163 ± 11 1,052 ± 144 187 ± 10 1,107 ± 142 71 ± 4 251 ± 30 83.5 ± 6 286 ± 41 786 ± 93 3,719 ± 378
Carboxymethyl chitosan —e — — — — — — — 1,184 ± 99 3,999 ± 500
a

Experiments were conducted in quadruplicate cultures. Experiments were reproduced a further two times with similar results (data not shown).

b

Both RPMI alone at pH 6.5 and chitosan solvent did not show any activity against amastigotes. Statistically significant differences were found between the EC50s of chitosan and its derivatives at pH 6.5 and pH 7.5 (P < 0.05 by using t test).

c

Chitosan and its derivatives had low cytotoxicities toward KB cells at both pH 6.5 and 7.5, and there was no significant difference in the cytotoxicities at these two pHs (P < 0.05 by t test). No statistically significant difference was found between LD50s (50% lethal dose) of the three types of chitosan and other derivatives against KB cells (except for carboxymethyl chitosan, which was the least toxic) (P > 0.05 by the extra-sum-of-squares F test).

d

Phosphorylcholine-substituted chitosan (see Table 4).

e

—, no activity up to 400 μg/ml.